As the world pays much attention to the greenhouse effect and energy crisis, how to utilize available energy more efficiently has become the subject of high interest worldwide. Almost all institutions, schools, factories, offices, and residences start to comply with the policies of governments for saving energy consumption and carbon emission. Thereby, the related power-saving lighting and solar lighting equipment are developed rapidly.
Solar lighting systems are applied to indoor or plant chamber lighting. It owns the characteristics of almost consuming no power and uniform spectrum. Thereby, it can solve the problems of LED lamps or T5 lamps in power consumption and nonuniform spectrum.
Traditional solar lighting can be classified into four types: 1. Introducing directly the sunlight using windows; 2. Reflecting and guiding the sunlight to indoor or plant chamber lighting using guiding pipes; 3. Using solar cells for power generation and using lamps for lighting; and 4. Using solar concentrators and light-guiding optical fibers to guide the sunlight to indoor or plant chamber lighting. Among the above methods, the drawback of introducing directly the sunlight using windows is that the sunlight cannot reach the plant chambers or locations indoors and away from the windows. The drawbacks of reflecting and guiding the sunlight to indoor or plant chamber lighting using guiding pipes are that the volume of the pipes is huge and the connection and installation of the pipes indoors or with the plant chambers are inconvenient. The drawback of using solar cells for power generation and using lamps for lighting is that low efficiency due to multiple conversions, including optical to electrical and electrical to optical conversions. Regarding to using solar concentrators and light-guiding optical fibers to guide the sunlight to indoor or plant chamber lighting, because the solar tracking and light guiding device is set on the ground, the length of the light-guiding optical fiber to the interior will be excessively long, which leads to high cost in the light-guiding optical fibers and hence retarding commercialization and promotion.
The Taiwan Patent Publication Number 1405928 discloses an illumination system guided by a light fiber through solar beams. This invention is composed of a focusing beams unit, a sun-tracking controller, a biaxial tracking mechanism, an energy transferring and storing unit, and a light fiber. At first, the sun-tracking controller scans solar beams and let the biaxial tracking mechanism track solar beams. Then, the focusing beams unit can guide light to the room by using the light fiber. Hence, the energy transferring and storing unit can generate power for system applications. Nonetheless, according to the invention, the focusing beams unit collects light reflectively. Consequently, when some incident light enters the radar-type reflection surface, it cannot be reflected into the light collection range, resulting in loss in light. The sun-tracking controller is an optoelectronic solar-location sensor. It might encounter the problems of failure or inaccuracy, leading to failure in tracking the sun. The angle of elevation of the biaxial tracking mechanism is disadvantageous to miniaturized and wall-mounted designs. Besides, the energy transferring the storing unit benefits little the solar lighting system at the expense of increasing the complexity.
Accordingly, it is required to provide a high-performance sunlight-guiding device to indoor or plant chambers and replace the traditional sunlight-guiding lighting system using optical fibers.